Reclining dental chair



Feb. 11, 1969 D. H. HALE RECLINING DENTAL CHAIR Sheet Filed Aug. 15,1966 Nah Feb. 11, 1969 HALE 3,427,072

HECLINING DENTAL CHAIR Filed Aug. 15, 1966 INVENTQR DEAN H. HALE UnitedStates Patent Ofi 3,427,072 Patented Feb. 11, 1969 ice 3,427,072RECLINING DENTAL CHAIR Dean Howard Hale, 2500 N. Main, Logan, Utah 84321Filed Aug. 15, 1966, Ser. No. 572,281 US. Cl. 297--342 4 Claims Int. Cl.A47c l /032; A61g /00 ABSTRACT OF THE DISCLOSURE A reclining dentalchair apparatus and method, the apparatus featuring a chair seat andback pivotally joined together and supported by a base, (a) the seatbeing power-driven to move rectilinearly to the base and simultaneouslypivot the back relative to the seat by force provided by the same powersource, or (b) the back being power-driven to pivot relative to the seatand simultaneously shift the seat oppositely and rectilinearly relativeto the base by force delivered from the same power source. The disclosedmethods comprise positioning a reclining dental chair so that thedisposition of the patients head remains within essentially onepredetermined and relatively narrow vertical corridor though occupyingany one of a plurality of relatively erect or reclined positions bydisplacing the seat relative to the base and simultaneously oppositelypivoting the back relative to the seat or vice versa.

The present invention relates to improved dental and like recliningchairs and more particularly to such chairs having improved positioncontrol features (a) for easily maintaining the patients head within aconvenient work region regardless of whether the chair is fully erect,fully reclined or at an intermediate position and (b) for automaticallyvarying the horizontal location of the center of gravity of the entirechair, including the occupant, relative to the base to compensate foroppositely varying the center of gravity of the patient in the chairresponsive to reclining or erecting the chair.

In the reclining dental chair and like arts, as presently constituted,it has become almost a medical necessity, for purposes of time, accuracyand convenience, that the position of the patients head at all times beessentially kept within a single, readily accessible work area, havingclose horizontal limits, without regard to whether or not the patient isupright or reclined. This enables placement of dental equipment,instruments, tools, materials, etc., in handy proximity, accommodateseasy direct-vision illumination at the Work site and accommodatesdirect, eflicient and accurate work by the dentist upon any region ofthe oral cavity without the need for mirrors, etc.

Prior known reclining dental chair proposals for maintaining theoccupants head within such a work area have been disadvantageous to use,requiring careful, manually coordinated actuation of several positioncontrols by the dentist to (a) recline the patient, in whole or in part,by pivoting the back of the chair relative to the seat of the chair and(b) to return the patients head to the requisite position between thementioned close horizontal limits. For example, see United States Patent3,150,898. Also, some commercial adaptations of such prior proposedreclining chairs have, for positioning purposes, required that the basewhich supports the chair be materially offset from the center of gravityof the chair. Consequently, such chairs require an undue amount of floorspace in the dentists ofiice and are economically burdensome because ofthe support and power actuating equipment must be constructed ofespecially heavy and/or strong materials to handle such offset loads.

The present invention novelly overcomes the abovementioned objectionablefeatures of the prior art by providing a reclining dental and like chairhaving improved position control features accommodating synchronous (a)reclining of the back of the chair and (b) automatic advancing of theentire chair relative to the base an adequate distance to compensate inforward motion of the chair for rearward motion of the back to keep thepatients head within the prescribed horizontal limits, and vice versa.Thus, the center of gravity of the patientsupporting chair is uniquelyand automatically repositioned each time the reclining position of thepatient (along with the patients center of gravity) is oppositelychanged, without manipulation of multiple position controls.

The presently preferred embodiment of this invention comprises a fluidor comparable motor interposed between the reclining chair and a fixedanchor position, such as at the support base. Either (a) the back of thechair is powered by the motor for pivoting the back relative to the seatwith a component of force, created by such pivoting, oppositely, thoughessentially rectilinearly shifting the entire chair relative to the baseor (b) the seat of the chair is powered by the motor for essentiallyrectilinear displacement relative to the base with a component of force,created by such essentially rectilinear displacement, oppositely, thoughpivotal relocating the back of the chair relative to the seat. Thus, bysingly controlling the one motor, the dentist may recline or erect thepatient as desired without displacing the patients head out of the workarea beyond the horizontal limits. A second motor is used to locate theentire chair at a suitable working elevation,

With the foregoing in mind, it is a primary object of this invention toprovide a novel dental and like chair system, including method andapparatus, having improved position control features accommodatingaccurate and convenient position regulation of the chair by the dentist.

Another significant object of this invention is the provision of a noveldental and like chair system wherein the center of gravity of the chairis automatically relocated to favorably reposition the chair relative toits supporting base each time the patient is reclined or erected, inwhole or in part.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims taken in conjunction with the accompanying drawings wherein;

FIGURE 1 is a schematic side elevation, partly broken away for clarity,of the presently preferred embodiment of this invention illustratingseveral positions in which the chair may be disposed by actuation of asingle motor;

FIGURE 2 is a fragmentary plan view taken along line 2-2 of FIGURE 1 ofthe motor and actuating linkage of the chair of FIGURE 1 which linkagecauses the back of the chair to be automatically pivotally repositionedeach time the position of the chair is rectilinearly altered relative tothe base by actuation of the motor;

FIGURE 3 is a fragmentary cross-section taken along line 3-3 of FIGURE1;

FIGURE 4 is a schematic side elevation of the second presently preferredembodiment of this invention, with parts omitted for clarity; and

FIGURE 5 is a fragmentary plan view taken along line 55 of FIGURE 4 ofthe motor and actuating linkage of the chair of FIGURE 4, which linkagecauses the chair to be automatically rectilinearly repositioned relativeto the base each time the pivotal position of the back of the chair isaltered by actuation of the motor.

Reference is now made to the drawings wherein like numerals are used todesignate like parts throughout. FIGURE 1 depicts a presently preferredreclining dental chair embodiment of the present invention, generallydesignated 10, adapted to situate a patient, generally designated 12, inany one of a plurality of variously reclined positions, as illustratedin FIGURE 1. Broadly, the chair has for its purpose the maintaining ofthe patients head 14 Within close horizontal limits so that the dentistsinstruments, tools, equipment, and materials may be situated in closeproximity to such a work area, the mentioned horizontal limits beingindicated by the position of the patients head 14 shown in solid linesand the lowest, fully reclined position of the patients head shown atthe left in dotted lines. The dotted head position shown to the right ofthe solid position is a manually-erected position quickly attained whenthe patient is choking or desires to express liquid from his mouth andis not a dental working position. In this way, the dentist may, with aminimum of time and inconvenience and with accuracy, complete his Work.

Structurally, the chair 10 of FIGURE 1 comprises a reclining back,generally designated 16, comprising a suitable rigid frame 18 includingsupport members running coextensive with the back and designated 20 andtransversely-extending cross members, including support member 22 whichis rectangular in cross-section and disposed at the bottom of back 16and near the pivotal connection 24 between the back 16 and a seat 26 ofthe chair 10. The back 16 preferably is suitably padded and upholsteredat the exterior 28, the type and nature of upholstery forming no part ofthe present invention.

The seat 26 of the chair also preferably comprises a suitable type ofexterior upholstery 30 and further comprises a rigid frame 32. The rigidframe comprises a plurality of cambered members 34 extending generallycoextensive with the seat 26 as well as the plurality of cross braces 36integrally joined, such as by welding or the like, to the camberedmembers 34. Thus, the frame 32 is an essentially rigid frame so that thepatient 12 is firmly supported thereby and the frame will move unitarilyto and fro across the base, which supports the chair, for purposes andin a manner subsequently to be explained.

A pair of depending hanger members 38 are integrally joined to the frame32, as for example by welding, and integrally carry a track 40 (FIGURE3) at one side near the lower end, suitably secured by welding or thelike. One such track is located at each side of the chair. Each track 40is rectangular in cross-section and, therefore, provides an essentiallyflat top surface 42 and an essentially flat bottom surface 44. The endsof both the left track and the right track are respectively integrallyjoined as for example, by welding, to the forward cross brace 36 and therear cross brace 36 so that each track 40 integrally forms part of theseat frame 32 and moves to and fro with the seat frame.

Also, the rear cross brace 36 at both sides, is integrally joined to apivotable lug 46 which in turn is pin-joined at 48 to lug 50, lug 50being integral with the back frame 18. Thus, the back 16 is pivotallyjoined at 48 on each side of the chair to the seat 26 so that thepatient 12 can be situated anywhere between a fully erected seatedposition and a fully reclined substantially horizontal position.

A skirt 52 may be disposed along each side of the seat 26 for appearanceand protection purposes thereby concealing the structural and workingparts disposed in beneath the seat 26.

The chair 10 is supported by floor-engaging base, generally designated60 with the relative horizontal positions of the chair and the basepreferably being such as to place the center of gravity of the chair, asnear as practicable, in vertical alignment with the base no matter towhat degree the patient is reclined. Of course, if desired, the base '60could be otherwise disposed relative to the chair.

The base 60 comprises a covering 62 adapted to conceal from view andenclose a fluid motor, generally designated 64, comprising a cylinder 66and a ram or piston rod 68. The sole purpose of the motor 64 is tosituate the entire chair 10 vertically at a suitable work elevation. Acontrol lever 70 is used in conjunction with a suitable conventionalhydraulic system (not shown) to selectively actuate the fluid motor 64.

As best seen in FIGURE 3, the piston rod 68 of the fluid motor 64 isintegrally joined to a base plate 72 from which a pair of right and leftroller support plates 74 integrally depend. It is to be appreciated thatwhile the base plate 72 is illustrated as being disposed in asubstantially horizontally extending orientation, the orientation couldbe inclined with respect to the horizontal so that the chair 10 would bedisplaced essentially rectilinearly in the direction of such orientationacross the base 60 as the inclination of the back 16 is modified, aswill subsequently become better understood.

Each depending roller support plate 74 carries a plurality of combinedtop and bottom roller assemblies, gene-rally designated and 82,respectively, at each side. Two of each such combined roller assembliesare illustrated as being situated along both the rig-ht and left handsides of the chair. Apart from location, the idler roller assemblies 80and 82 are identical and therefore only one will be explained.

The roller assemblies 80 and 82 each comprise a commercially availableroller 84, the circumferential surface 86 being in contiguousfriction-bearing relationship with the respective surfaces 42 and 44 ofthe track member 40. The roller 84 is joined by means of a suitablebearing (not shown) to a short shaft 88 which passes through an aperture90 suitably located in the adjacent depending roller support plate 74.The interior terminal end of the short shaft 8 8 is threaded at 92 andthreadedly receives a nut 94 which is secured in its tightened positionby a lock washer 96. A spacer 100, interposed between the plate 74 andthe bearing (not shown) of each roller 84 maintains the roller surface84 in proper alignment with the track 40. A nylon or other suitablelongitudinally extending guideblock 102, secured to the adjacent plate74 by means of countersunk bolt assemblies '104 passing through anaperture 106 in the plate 74, also accommodates aligned displacement ofthe seat 26 relative to the base 60. Thus, the top and bottom rollerassemblies 80 and 82 accommodate fore and aft displacement of the chair10 across the base, the track 40 being lineanly displaced through thetop and bottom rollers at such time to create opposite rotation of theidler rollers 84 of the assemblies 80 and 82. Thus, the presentconstruction avoids any need for pivotal connection between the base andthe chair.

A position-controlling hydraulic motor, generally designated 120, isinterposed between the base plate 72 and the seat frame 32 (FIGURE 1)for the purpose of displacing the chair relative to the base when it isdesired to reposition the degree of patient recline. The full stroke ofthe piston of motor determines the forward and rear extreme positions ofthe chair with respect to the base. More specifically, the fluid motor120 comprises a cylinder 122 from which a piston rod 124 extends. Thebase of a cylinder 122 at integral anchor the lugs being integrallyjoined to the base plate 72, as for example by welding. Thus, thecylinder 122,

is held in an essentially stationary position by such union with thebase plate 72.

On the other hand, the piston rod 124 is pivotally joined at pin 132 toa link 134, which link is integrally joined to the seat frame 32 at therear cross member 36. The cylinder 122 is a two-way cylinder of con-.ventional type accommodating both forward and rearward displacementunder control of the dentist using suitable means including asatisfactory conventional hydraulic system (not shown) and a controllever (not show-n) or the like in a manner generally well known in theart.

A linkage system, generally designated 140, is interposed between theback 16 and seat 26 of the chair and anchored to the base 60 for thepurpose of pivoting the back 16 relative to the seat 26 in response toand to an extent commensurate with the magnitude of any rectilineardisplacement of the seat across base 60 caused by actuation of the fluidmotor 126 through either extending o-r retracting the piston rod 124.

tl he linkage mechanism 140 (best seen in FIGURES l and 2) comprises alink 142, integrally and rigidly depending from the frame 18 of the back16 at the lower cross member 22, and a telescopic member 144 comprisingan outer hollow tube 146 and an inner rod 148, the rod being disposedwithin the hollow of the tube. The left end of the telescopic tube 146is pivotally joined, using clevis and a pin 150, to the link 142 and theright end of the rod 148 is joined, to a diagonal link 158 at swivelconnection 160. If desired, a one-piece member may be used in place ofthe two-piece telescopic member 144.

The diagonal link 158 by means of an end connection 164, is rotatablysecured near the mid point thereof to a support block 162, which blockis integral with the frame 32. The other end of the diagonal link 158 ofthe linkage system 140 is pivotally joined at pin 166 to a link 170which extends generally parallel to the telescopic member 144 but issituated at the opposite side of the chair. The rearward end of the link170 is pivotally joined at pin 172 to an anchor bracket 74, whichbracket is suit-ably integrally secured to the base 60 so at all timesto be situated in a stationary position.

with the foregoing in mind, the operation of the chair 1!), asillustrated in FIGURES 1, 2, and 3, will now be described. It is to beappreciated that the patient 12 may be reclined or erected in any one ofan infinite number of positions between the fully erected and the fullyreclined positions, the fully erect position being illustrated with thepatients head shown in solid lines at 190 (FIGURE 1) and the fullyreclined position being illustrated in dotted lines at 192. Theseintermediately reclined head positions are also illustrated at 1'94, 196and 198. It is also to be appreciated that as the fluid motor 120, undercontrol of the dentist, powers the seat 26 to and fro as desiredrectil-inearly across the base in a direction defined by the orientationof the base plate 72, a component of force caused by such rectilineardisplacement will be transmitted through the linkage system 140 topivotal ly relocate the back of the chair relative to the seat an amountproportional to the rectilinear distance traversed. Thus, by singlycontrolling the one fluid motor 120, the dentist may synchronouslydisplace the seat 26 along with the back 16 forward relative to the base60 and at the same time and under power of the same motor, through thelinkage system 140 as accommodated by the counterclockwise momentexerted by the patient upon the back 16, recline the back 16 acor-responding amount. Where a one-piece memher is used in place of thetwo-piece telescopic member, the moment exerted by the patient upon theback is irrelevant when reclining or erecting the back.

Likewise, when under control of the dentist, the fluid motor 120 powersthe seat 26 back, or to the left as viewed in FIGURE 1, relative to thebase 60, the same power provided by such actuation of the motor 120 willdisplace the linkage system 140 causing the back '16 to be erected adistance proportional to such rear rectilinear displacement of the seat.Hence, the center of gravity of the chair, with patient residingtherein, will be automat-ica-lly relocated in a favorable and easilysupported reposition with respect to the base '60 each time the patientis reclined or erected, in whole or in part, in the opposite direction.Therefore, the offset distance between the force of the combined centerof gravity of the chair and patient and the reaction force exerted bythe base 60 will be minimal at all times.

More specifically, when the dentist actuates' the fluid motor so as todisplace the chair 26 toward the right relative to the base 60sufficient to bring the pivotal connection 40, from the solid position200 to the dotted position 202, the right edge of the seat 26 will bedisplaced from the position 294 to the position 206 (FIGURE 1), theswivel connection 160 will be displaced from the position 208 to theposition 210 (FIGURES 1 and 2), the central pin connection 164 of link158 (FIGURE 2) will be displaced by movement of the seat 26 from theposition 212 to the position 214, the pivotal connection 166 will bedisplaced from the position 216 to the position 218 (FIGURE 2), and thepivotal connection (FIGURE 1) will be displaced from the position 220 tothe position 222.

The mentioned displacement of the connection 150 from the position 220and to position 222 will cause counterclockwise rotation of the link 142about pin connection 48, as viewed in FIGURE 1, reclining the back 16from the position 224 to position 226 and altering the head 14 of thepatient 12 from 190 to 194 (FIGURE 1), thereby retaining the head 14 ofthe patient within close horizontal limits so that the dentist mayconveniently and accurately work on any region of the oral cavityWithout relocating his tools, instruments, materials and the like andwithout appreciable inconvenience or loss of time.

In like manner, the fluid motor may be actuated to advance the seat 26rectilinearly within its limits of operation to any desired position andto correspondingly recline the seat 16, as, for example, by causingdisplacement of the pivot connection 48 to any of the positions 230,232, and 234, and, accordingly, causing the right front edge of the seat26 to be situated at positions 236, 238, and 240, respectively;relocating the swivel connection at positions 242, 244, and 246,respectively; disposing the central joint 164 at the positions 248, 250and 252, respectively; displacing the pivotal connection 166 serially tothe positions 254, 256, and 258, respectively; correspondinglydisplacing the pivotal connection 150 to the positions 260, 262, and264, respectively. Such combined displacement will rotate the link 142counterclockwise about pin connection 48 repositioning the back 16 atthe pivoted locations 266 and 268 and 270, respectively. This willcorrespondingly dispose the patients head 14 at the positions 196, 198,and 192, respectively.

The same procedure may be followed in reverse with opposite actuation ofthe motor 120, under control of the dentist, to selectively erect theback 16.

Occasionally, for example, when a patient is choking, it is desirable toquickly move the patient from a reclined to a fully erected position.This can readily be accommodated because the telescopic member 144enables free upward pivotal movement of the back 16 relative to the seat26 while the seat 26 remains generally stationary. Thus, the dentistneed only manually grasp the underside of the back 16 and manually liftthe back. This will pivotally displace the back 16 around pin 48 andcause the members 146 and 148 to extend telescopically. Therefore, forexample, when the back 16 of the chair is disposed in the fully reclinedposition 270 (FIGURE 1) and the patients head 14 is located in theposition 192, and the patient is choking, the dentist may manually liftthe back 16 pivoting the back relative to the essentially stationaryseat into the erect position designated 272 in FIGURE 1 thereby placingthe patients head in position 274. Thereafter, the patient may again bereclined, the dentist merely releasing his manual support of the back 16allowing the member 148 to inwardly telescope into the hollow cavity ofthe member 146, air escaping from the cavity through a suitably sizedaperture (not shown) located at the end of the member 146 near the pivotpin 150.

Reference is now made to FIGURES 4 and 5 which depict a second presentlypreferred embodiment of the present invention. Much of the structurepreviously explained in conjunction with chair 10 of FIGURES 1-3 mayalso comprise part of the chair, generally designated 300, of

7 FIGURES 45, and such corresponding structure will not again bedescribed. For example, the base (including the frame and the rollerassemblies), the back, the seat, and the pivotal connection between theseat and the back may be the same in each chair embodiment.

Fundamentally, the chair 300 differs from the chair 10 in that the backof the chair is powered by a single motor for pivotal displacementrelative to the seat, with a component of force created by such pivotingoppositely though essentially rectilinearly shifting the entire chairrelative to the base. In the previous embodiment, chair 10, the seat wasrectilinearly powered, as opposed to pivotally powering the back as isdone with chair 300.

structurally, the two-way fluid motor 302, comprising a cylinder 304 anda piston rod 306, is interposed between the frame 32 and seat 26 and theback 16, the piston rod 306 being pivotally joined by pin 308 to thedepending integral link 142. The cylinder 304 is integrally joined,through lug 310, pin 312 and anchor bracket 314, to a pair of diagonalframe members 316 and 318. The frame members 316 and 318 are integrallyjoined, as for example by welding, to the frame 32. Thus, under controlof the dentist, actuation of the motor 302 to advance and retract thepiston rod 306 will in turn rotate the link 142 along with the back 16clockwise and counterclockwise, respectively, around pin 48, as viewedin FIGURE 4, thereby controlling the pivotal disposition of the back 16relative to the seat 26.

A linkage system, generally designated 320 is interposed between theback 16 and the seat 26 and is anchored to the base 60 so that the seat26 will be automatically rectilinear through oppositely displaced as theback 16 is reclined or erected, in whole or in part, responsive toactuation of the motor 302. Structurally, a swivel connection 322pivotally joins a lug 323, which lug integrally depends from the frame18, to the linkage system 320 at recessed block. The block 324 isintegrally attached to the left end of the link 330, as viewed inFIGURES 4 and 5.

The link 330 is rotatably joined at pin connection 332 to a diagonallink 334. The diagonal link 334 is joined at pin 336 for pivotalmovement relative to the seat frame 32, the pin 336 being retained in ananchor bracket or lug 338 integrally fastened to the seat frame 32. Theopposite end of the diagonal link 334 is pivotally joined at pinconnection 340 to a link 342 which extends generally parallel but offsetfrom the link 330. A pin connection 344 joins the back end of the link34-2 to an anchor bracket 346 which is suitably integrally secured tothe base 60 of the chair.

The operation of chair 300 is essentially identical to the operation ofthe chair 10 previously described, except that actuation of the fluidmotor 302 alters the pivotal position of the back 16 relative to theseat 26 and such actuation, through the linkage system 320, causes theseat 26 to be essentially rectilinearly displaced across the base 16 ina direction opposite to the pivotal change of the back 16. Thus, usingthe chair 10, actuation of the motor 120 rectilinearly displaces theseat 26 across the base thereby causing the back 16 to pivot an amountproportional to such rectilinear displacement; and, using the chair 300,actuation of the motor 302 pivotally repositions the back 16 relative tothe seat and thereby causes the seat 26 to be rectilinearly displacedacross the base responsive to such displacement.

It is to be appreciated that the link 330 of the linkage system 320could comprise telescopic members to accommodate rapid manual erectionof the back 16 when the patient is choking or the like. Using suchtelescope members, it would be necessary that the base plate 72 beinclined somewhat with respect to the horizontal so that when undercompression the telescopic members comprising link 330 will be displacedunitarily counter to gravity as the back 16 is reclined and when undertension one such telescopic member will move responsive to the force ofgravity generally in unison with the forced displacement of the othertelescopic members induced by erection of the back 16.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are, therefore, to be considered in all respects asillustrative and not restrictive. The scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore to be embraced therein.

What is therefore claimed and desired to be secured by US. LettersPatent is:

1. In a base-mounted, reclining dental chair and the like adapted tomaintain a patients head Within a convenient working area betweennarrowly spaced vertically extending limits without regard to therelative orientation of the components of the chair comprising a backportion pivotally associated with and supported in cantilever relationat the rear of a seat portion of the chair, antifriction meansinterposed between the seat and the base accommodating ready selectivedisplacement of the chair across the base, a selectively operable singlepower mechanism interposed between a fixed anchor and the chair andlinkage interposed between the back and seat of the chair and the baseaccommodating reorientation of the patient and the chair by concurrentdisplacement of the chair across the base and pivoting in exact timerelation of the chair back relative to the chair seat intermediate anerect nearly vertical position and a fully reclined substantiallyhorizontal position, and other selectively operable power means solelyfor changing the elevation of the chair.

2. In a method of manipulating a base-supported dental or like chairhaving a back movable from a substantially vertically erect position toa substantially horizontally reclined position comprising the steps of:(a) lowering the headrest portion of the back of the chair essentiallyvertically downward within a narrow vertical corridor intermediate theerect and reclined positions by synchronously (l) arcuately pivoting theback downwardly relative to the seat about a pivotal axis disposed inthe region between the back and the seat with the back beingcantilever-supported only in the mentioned region and (2) jointlyadvancing the back and the seat across the base so that the effectivehorizontal rearward movement of the headrest portion is substantiallyequal to the effective horizontal forward movement of the seat at anyinstant of time during the pivoting and advancing, (b) elevating theheadrest portion of the back of the chair essentially vertically upwardwithin the narrow vertical corridor intermediate the erect and reclinedpositions by synchronously (l) arcuately pivoting the back upwardlyrelative to the seat about the pivotal axis and (2) jointly rearwardlydisplacing the back and the seat across the base so that the effectivehorizontal forward movement of the headrest caused by the pivoting issubstantially equal to the effective horizontal rearward displacement ofthe seat at any instant in time during the pivoting and displacing.

3. In a reclining chair for retaining an occupants head at any selectedone of several available elevations within close horizontally spacedlimits no matter how the chair is inclined relative to the vertical, thechair comprising a back portion and a seat portion, the back portionbeing mechanically movable through pivot action between a primarilyvertical disposition and a primarily horizontal disposition, a baseinterposed between the floor and the seat of the chair, antifrictionmeans supporting the chair for essentially rectilinear displacement toand fro across the base, selectively-controlled motor means disposed todirectly displace one said chair portion in the manner mentioned betweenavailable positions, and pivotally-related linkage means disposedgenerally beneath the seat and interposed between said chair portions,said linkage restraining the other chair portion in a selected positionwhen the motor means are inactive, said displacement of the one chairportion causing the linkage at least in part to follow said one portionwhen the motor means are active with the linkage follow actionaccommodating the mentioned displacement of the other chair portion toretain the occnpants head within the close horizontally spaced limits atall times.

4. An apparatus as defined in claim 3 wherein said linkage meanscomprises telescopic members adapted to be telescopically extended bymanually elevating the back relative to the seat while retaining theseat in an essentially stationary position so that the occupant may bepromptly moved from a reclined position to an erect seated position,when desired.

References Cited UNITED STATES PATENTS 1,822,427 9/1931 Wenn et a1.297342 1 0 2,028,633 1/1936 Thomas 297-622 3,172,699 3/ 1965 Naughton297330 3,222,105 12/1965 Cross 297-314 3,224,808 12/ 1965 Spielman297-378 3,232,575 2/1966 Ferro 297--329 3,329,463 7/1967 Zimmerman 297342 FOREIGN PATENTS 15,112 9/ 1897 Switzerland.

US. Cl. X.R.

